CHRISTCHURCH, New Zealand - After having withstood major earthquakes in recent years, the third largest city in New Zealand is reeling again, this time after a massive and shocking mass shooting hit the city on Friday afternoon.

At least forty nine people have been confirmed dead, and 48 injured, after gunmen opened fire on two mosques close to the city centre.

The entire city has gone into lockdown as improvised explosive devices (IEDs) are being retrieved and decomissioned from across the city. Many of them attached to vehicles.

One of the gunmen, understood to be an Australian, reportedly filmed the killings at the Al Noor Mosque as they occurred before posting the video on social media.

Four people have been arrested so far, 3 men and a woman.

The New Zealand Police Commissioner Mike Bush says there have been "multiple casualties,`' a "significant number."

"This is absolutely tragic. So many people are affected," he said.

"We don't have the identities of those who have died yet because those places are in lockdown."

The commissioner said he not could rule out other attackers still on the loose.

The lock down of schools throughout Christchurch was lifted at 5:50pm Friday.

Bush said he was aware that footage of the Al Noor Mosque shootings was on social media and police were doing everything they could to get it removed. "It shouldn't be in the public domain," he said.

"We are currently dealing with an unprecedented situation in New Zealand. It's very grave, it's very serious."

"It is clear that this can only be described as a terrorist attack. From what we know, it does appear to have been well planned. Two explosive devices attached to suspects' vehicles have been found and they have been disarmed," Prime Minister Jacinda Ardern said Friday night.

"There are currently four individuals who have been apprehended but three are connected to this attack and are currently in custody, one of which has publicly stated that they were Australian-born," said the New Zealand PM.

"These are people who I would describe as having extremist views that have absolutely no place in New Zealand and in fact have no place in the world."

"While we do not have any reason to believe at this stage that there are other suspects, we are not assuming that at this stage," Ardern said.

Christchurch is New Zealand's third-largest city after Auckland and the capital, Wellington. It is the largest city in the South Island.

Christchurch was the scene of major earthquakes between September 2010 and early 2012, during which 185 people were killed.